Literally anything? On many of the machines I have written emulators for, most things are usually completely changeable but some things are loaded internally — especially on any machine that has a variable screen start address.
Also, one further question: am I right to think that the Sam has no means of producing interlaced video? On Wed, May 21, 2008 at 3:58 PM, Andrew Collier <[EMAIL PROTECTED]> wrote: > On Wed, May 21, 2008 at 03:16:07PM +0100, Thomas Harte wrote: >> If you interrupt routine is small, could you not also just switch off >> the first one or two scanlines of your display, and even grab a few >> extra cycles out as a result? Or can you not enable and disable the >> display per scanline? > > Hi, > > You could, yes. You can alter pretty much anything about the screen on a > line-by-line basis - and if you're very careful, during those lines in the > screen area itself! For example, MMENOdemo 1 part 2 (on Fred 60) changes the > screen page during the raster; repeatedly switching between foreground and > background screens to draw lit and unlit rectabgles - which togehter form a > scrolling message. > > Various other programs switch between mode 4 and mode 3, to get high > resolution in a certain area of the screen - Edwin Blink's menu on Blitz > (issue 6, was it?) and David Laundon's Fred menu come to mind. > > Anyway - in this particular case I wanted to display the whole screen; and in > the case of one or two scanlines, it probably takes longer to set up the line > interrupt handling, than you save by having the screen turned off. > > Cheers, > Andrew > > -- > --- Andrew Collier ---- > ---- http://www.intensity.org.uk/ --- > -- > r<2+ T<4* cSEL dMS hEn/CB<BL A4 S+*<++ C$++L/mP W- a-- Vh+seT+ (Cantab) 1.1.4 >
